Regarding the 404 failure while visiting re-generated topic URLs, Kolya suggested it might be a cyrillic “mixin” like http://www.myawsomenewforum.ru/форум/topic/51156/
Unfortunately switching all forum slugs to latin like (www.myawsomenewforum.ru/forum/topic/51156/) doesn’t do the trick, it’s still 404 for me.

Yes, I am sorry we kinda forgot this forum is mostly in English still
Kolya’s advice to flush permalinks while deactivating all plugins and so on combinations, .trashing and recreating .htaccess didn’t work out yet, must be something with my bbPress but I have a long autumn night going ahead which is nice..

Positive and positive. Now I’ve just made a clean install in English and set permalinks to postname. All works just fine, but right after activating the plugin all new nicely regenerated urls such as domain.com/forums/forum/11 or domain.com/forums/topic/13/ lead to 404. Unchecking forums/ prefix and flushing permalink settings doesn’t help. My wordpress installation directory is domain root, bbPress installed via plugin.

Maybe I can help you by providing more technical details from somewhere?

Thank you but nope. Still no luck. See eg. http://pupyshevo.hol.es/forums/forum/11/
Maybe some debugging? You can use my credentials on this test site, would be glad to help! Let me know and thanks again for proper support!

Oleg

PS: flushed permalinks with default and then with postname. Also reactivated both bbPress and the plugin. Still believe it isn’t really plugin’s fault, but me doing smth wrong…